This invention relates to a trolley conductor bridging means in an electrically powered trolley vehicle transportation system where said trolleys run by contact with a solid conductor. More particularly, this invention relates to such bridging means that when closed provides continuous electrical power and mechanically indistinguishable connection across a door clearance opening between said conductors and where said bridging means is opened and closed automatically by the passage of a door transverse to said conductor with said door remaining electrically non-conductive.
In the operation of electrically powered trolley systems where the trolleys run by contact with a solid conductor, any necessary interruptions in said conductors to allow for the closing or opening of gates, doors or crossing arms etc. has always presented problems. For example, it has always been a problem as to how to provide power throughout the system while also providing openings between the conductors through which the aforementioned devices could cross. It has also been a problem as to how to keep the crossing devices electrically inactive while crossing the electrically active trolley conductor. It has further been a problem as to how to provide no encumbrances to smooth passage along the trolley conductor when said interruptions between the conductors have been bridged.
In addition, so as to not to require the presence of a separate operator for such bridging means, it has also been necessary that such bridging means be opened and closed automatically. Further, since the location of such bridging means can at times be very inconvenient and difficult to access, it has also been demanded that such bridging means be mechanically simple in design and require little or no maintenance and/or repair.
A number of different types of trolley conductor bridging means are known in the art. Such means in one field of application have been used to provide mechanical bridging of a trolley guide rail where the path of the trolley was directed by travel along the guide rail and where a break in that mechanical guide rail was demanded to allow passage of an overhead steel curtain. The U.S. Pat. No. 779,554 to R. T. McCarroll discusses such a means. McCarroll provides a lever controlled mechanical bridging apparatus for the automatic opening and closing of the non-conductive guide rail bridge link to allow passage of a steel curtain. As an integral art of this bridging apparatus, McCarroll uses the container mechanism of the steel curtain to support the guide rail with the position of the container being critical to the alignment of the steel curtain with the bridge actuating lever.
This bridging system, though, is designed for use in a mechanical application only and in that application for use with the integral steel curtain and its container. Such bridging system, by design, would be ill-suited for an electrical conductor system.
For instance, in electrical conductor systems it is well known that a major concern in the design of such a system is the electrical insulation and isolation of the electrically active conductor from its surroundings. From the above disclosure it is evident that such insulation and isolation are not present. For one, the steel curtain due to its integral attachment to the rail conductor would be electrically conductive at all times. Such a conductor system is therefore impossible to use, since anyone touching the door would be electrocuted and since anything in subsequent contact with the steel curtain would also become electrically active. Further, such apparatus would be unsuitable for use in a mine tunnel for the like, since the lever actuator design of the bridge provides unneeded additional mechanical complexity with its associated additional repair and replacement problems.
Automatically door actuated electrical conductor bridging mechanisms were heretofore unknown in the art. While a variety of electrical conductor bridging means are known in the art, none disclose the door actuated bridging means of this invention. Examples of electrical conductor bridging means are U.S. Pat. No. 450,687 to E. Thomson, and U.S. Pat. No. 1,010,096 to T. Varney.
The Thomson patent discloses a motor operated gate-like conductor bridge for openings in an overhead conductor line. This invention is extremely complex requiring timing, coordination and actuation of several electrical components with the trolley vehicle to effect said bridge.
The Varney Patent discloses a lateral lever bridge which maintains the alignment of the trolley rails, where because of their separation, such conductors have become misaligned. In addition to the lateral bridge, the Varney patent requires a separate knife switch to provide electrical power across said separation. This invention is inoperable with an overhead door because of the interference of both said knife switch and said lateral bridge with the travel of said door and is further ill suited for use in a mine or the like by requiring manual actuation.